One of the problems with outside water faucets on buildings located in cold climates is that they are often subject to freeze damage. In order to avoid freeze damage, the outside faucets are construted with internal shutoff valves that are located on the warmer interior of the building. The internal shutoff valve includes a valve and a valve seat for shutting off the flow of water in the portion of the water supply pipe located in the interior portion of the building. An interior located shutoff valve permits the water from the water supply to be shut off in the portion of the water supply pipe located on the interior of the building where the temperature remains above freezing. If no hoses or other attachments are connected to the faucet, shutting off the water supply inside the building also permits the water downstream of the internal shutoff valve seat to drain out through the faucet spout. Consequently, in the event of freezing conditions, there is not any water in the outside portion of the faucet to freeze and rupture the water pipes or the water faucet. However, freezing problems can occur with such prior art freeze-proof faucets, particularly, if there are hoses or backflow prevention devices connected to the water faucet. The present invention addresses the freezing problem when devices are attached to the water faucet.
In certain hookups the prior art backflow prevention valves do not permit an automatic self-draining of the faucet, i.e., the backflow prevention valves connected to the faucet spout do not automatically permit water to drain out of the faucet housing located between the outside spout of the faucet and the internal valve seat when the water pressure is shut off. Consequently, if the temperature drops below freezing and the faucet has not been drained, the water in the faucet may freeze and rupture the water pipe or the faucet.
In order to minimize the freeze damage to faucets and water pipes, some backflow prevention valves have been provided with a manual drain system so the water can be drained from the faucet. The present invention eliminates the need for a manual drain system when using backflow prevention valves by providing a backflow prevention valve that automatically drains the water in the faucet even though the faucet may be connected to a hose or the like.